A light emitting element is generally packaged from the standpoint of protection from outside forces, control of the angle of beam spread of the emitted light, supply of electric power to the light emitting element, and the like (for example, refer to Patent Document 1).
FIG. 4 is a drawing that shows an example of a conventional light emitting element package configuration, with this package configuration being constituted by a package 5 which has a reflective concave portion having a sloping surface for making the light emitted from a mounted light emitting element 1 radiate ahead efficiently, and a pair of electrodes 4 for energizing the light emitting element, the light emitting element 1 such as an LED that is mounted in this package 5, a thin metal wire 2 that electrically connects the light emitting element 1 that is fixed on one of the electrodes 4 and the other electrode 4, and a transparent sealing resin 3 that is filled in the reflective concave portion of the package 5 for sealing the light emitting element 1 from the outside air.
Moreover, in the case of a white LED, a mounting method that is generally employed includes combining a yellow light emitting fluorescent material excited by blue light such as yttrium aluminum garnet fluorescent material with a blue light emitting element that is a nitride system compound semiconductor like InGaN, and in the case of the configuration shown in FIG. 4, it is common to mount the fluorescent material by distributing it in the sealing resin 3.
On the other hand, in order to increase the light emission intensity of light emitting elements such as LEDs, it is effective to increase the heat radiation performance of the package. The light emission efficiency of a light emitting element per unit power consumption is still low with the present technology, and because the electric power that does not contribute to luminescence is converted into heat, the light emitting element itself generates heat. A light emitting element is a kind of semiconductor, and the efficiency of light emission falls as its temperature rises. Therefore, by enhancing the heat radiation performance of a package such as the substrate for mounting the light emitting element, it becomes possible to impress a still larger current to the light emitting element, and, as a result, it is possible to elevate the light emission intensity per light emitting element. Examples of a substrate with a high heat radiation performance include an aluminum nitride substrate and a metal substrate which uses metal for the core.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. S62-224986
Patent Document 2: Japanese Patent, Publication No. 3511987
In a white LED mounted by a method of combining a yellow light emitting fluorescent material excited by blue light with a blue light emitting element, in the case of a conventional configuration that adds the fluorescent material to a sealing resin as described above, when the addition amount of the fluorescent material to be mounted is not constant, or even if the addition amount is constant with respect to the resin, because the amount of the resin to be mounted that includes the fluorescent material varies, the balance between the blue light emitted from the light emitting element and the yellow light emitted from the fluorescent material is lost, and so as a result, the color chromaticity becomes unstable. Furthermore, the fluorescent material may become settled down in the resin, leading to variations in the emitted color. Due to such variations in the color chromaticity, for those that deviate from the target specifications during mass production, countermeasures need to be taken such as treating them as defective or selling them according to a chromaticity classification, which is a problem leading to an increase in production steps, and moreover, there is the problem of large-scale production of white LEDs within a desired chromaticity range being difficult.
On the other hand, a method of mixing a fluorescent material in a resin has been proposed (for example, refer to Patent Document 2). Patent Document 2 discloses that, in order to suppress chromaticity variation, the fluorescent material is sufficiently mixed in a resin with a device such as a roll mill, and thereby the dispersion state of the fluorescent material in the resin becomes stable, and as a result the variations in chromaticity are greatly reduced. Although reduction of the variation in chromaticity can be said to be achieved by this method, in this conventional method, since long hours is required for mixing and the manufacturing hours is extended, the manufacturing cost increases in terms of manufacture of the product, and it is necessary to purchase a device for kneading the resin in which the fluorescent material has been mixed.
The present invention was made in view of the above circumstances, and has as an object of providing a light emitting element mounting substrate that readily enables manufacture of a high quality light emitting element package with minimal chromaticity variation when manufacturing a white LED, a light emitting element package that is formed by packaging a substrate together with a light emitting substrate mounted thereon, and a display device and illumination device that employs this light emitting element package.